We have come with increasingly creative uses of servodrivers. For example, there are now little vacuum cleaners that can travel around your house unsupervised. These robot vacuums can travel at a constant speed, so they know the floor is clean.

They are used in hard disc drives and your DVD player to maintain constant disc speed. A servodriver mechanism is a motor with a speed sensor attached.

In large ships (aircraft carriers etc.) if the sea makes the ship roll a mechanical or laser gyro sends a signal to the underwater vanes that maintain the horizontal attitude of the ship so that aircraft can land more safely on deck.

It's exactly the same as your brain making you swim in a straight line.